Transformer construction



March 16, 1954 L. VERKUIL TRANSFORMER CONSTRUCTION Filed Feb. 24, 1951Patented Mar. 16, 1954 UNITED STATES PATEN T FICE TRANSFORMERCONSTRUCTION Leo L. verkuil, Norwalk, Conn., assignor to Edwards=Qompany, :Inc., Nor-walk, Conn, a-cor- ;poration.of.New.Yor-kApplication=Eebruary 24, 1951, Serial No.212,609

27 rGlaims. (Cl. 317-) :TIZhis invention relates'rtorthe constructionand mounting ;of electrical :t-ransformers .and :to .casings :thereior..application iis :a zrcontinuation-in-part 'of my application 'Serial:Number 'LBGOZ; filed January 19, 319,49, now abandoned.

;More :panticularly, it relates ftO (that itype .of transformer which is:adapted :to :be secured to an toutlet .box 101' ,to be 'TSEOUIBd tO abracket or cleat on -.a :wall. Generally speaking, the :type of:transformer forzwh-ich the present .invention is :particularlyiuseful:is :the type used to :reduce the voltage :o'f, 'illustratively, therordinary house lighting supply circuit (1 15 :or '23!) volts) to alower moltage say, i 6 ivolts or .24 -yolts, for use in a bell-ringingor other signalling system or other low avoltage utility.

:Erior art transformers of the tt-ype with which the present invention.is generally concerned are subject to a number of serious .defects.:Such prior art transformers have been :designed with pedestals attachedLthereto Yfor amounting on a wall bracket or cleat, and expedients havebeen attemptedso "that, without use -='of the :pedes'tals, the"transformer :may he attached to a standard outlet lbOX and secured"thereto. However, when attached :in this -manner Iit has ibeemposs'iblethat some portion of the'itransformer is closer *to the wall or otherstructure-on which the outlet box is mounted 2 than isconsistent with:safety, I-having in consideration .the hazard from lfire. Forexample,Underwriters Laboratories,Inc., th'e recognized; authority sonthe construotion and installation of :olevioes *which under somecircumstances may :become fire .ha-zards, has specified a minimumdistance .fromanytpart'ofia transformer so mounted to the :nearest-wal1. l hat authority prescribes :the :standard :minimum distance fortransformers rofithe above-described type as onequarter of an inch.

An object of the ;present inven'tion is to pro-, vide :a transformerconstruction which has a mounting :pedestal iintegral with :the casing:02? the transformer and which is -.capable of being readilyinterrelated with a standard outlet box, but cann'ot be :mounted 'orsecured ito it in any position with-out maintaining a :minimumpredetermined clearance between the transformer :itself and the wallupon which the :outlet :box is mounted.

.iAnother object is to :provide .a transformer construction in whichtheam'eans for mounting it on :an outlet box 531 8 of simple landreadily Efabricated {construction and -simp1e.=and 'JCOIIVBHTEIIC tomanipulate, and, edesirably, have mo parts such as =bdlts :or muts whichmust :be removed Gil 2 when 'cmounting it, yet assures that ithe:transformer is tightly and positively secured Eto rthe outlet box.

.Another ObjGCtzlS to :provide suchrattransformer construction which iseasy :and economical ito construct and .to install and \which hasEinherent safety in use. Another object :is to ":provide a transformerconstruction :in which the meavy lead wires, such as those that :are tobe connected inside the outlet box, are strongly :and dependablyanchored and well :adapted :to :resist pulling thereof or strains:thBI'BOIl. .AIIUthEriOb' ject is to provide atransformer of athejust-unentioned ttype embodying, in a compact :manner and capable ofease of assembly, :a temperatureresponsive cut-out which :may also :be'adapted to serve as :a lead-in anchorage :and which may be ;constructedin a 'manner readily to :compensate for possible strain :imposedithereon during assembly.

:Other objects will :be in part tobvious :or 'in part pointed (out"hereinafter.

The invention "accordingly :consists in the zfeatures ;of construction,combinations ooi elements, and arrangements of :parts as will sheaexemplified in the structure :to the :hereinafter described and thescope of the application :of which will be indicated iinithe followingclaims.

:In the accompanying :drawing in which :is shown an illustrativeembodiment of ithis invention and in which similar reference characters:re'fer .170 :similar "parts throughout,

Figure ,1 .is a perspective view :of :the transformerstructure :and :ofan outlet :box, showing the .iformer in .a position ready to be securedto the :outlet 'zb'ox;

.Ei'gure i2 is :a plan :view :as seen along the zline 2-+2 of Figure :1,with the 'outlet .b'ox :shown tin horizontal section, showing thetransformer structure assembled to wthe outlet .abox, an .in relation:to the "wall or other supporting -surfaoe to which the :outlet bnx issecured;

Figure .3 :is ansendoelevation zof the transformer structure .as itwould rbe seen from the :left iin Eigure 2 :prior =.to its assemblageitothe "outlet ib'ox';

Figure A is a plan :view 50f sthe transformer structure as .seen with :aportion of tits ceasing structure zremoved;

rzli'igures *5 and 61are transverse :sectional 'aviews as seena1ong'the;line;AxA :ofsFigure lpfihowing by way of illustration twoforms iofspreader aarrangements for icertainof the transformer idasingparts;

anigures :7 and 1:81am yplan views mes,pectmelt of ea sheetemetal-.conductor rclamping plate and of a coacting insulating plate which areassembled and related to the core and winding as shown in Figure 4;

Figure 9 is a detached side elevation, seen from the left of Figure 4,.of a temperature-responsive switch structure, and

Figure 10 is a vertical sectional view as seen on the line 8--8 ofFigure 9.

The transformer comprises a core C, illustratively laminated and of anyusual form, generally rectangular in outline as shown in Figures 1, 2,and 3, and a casing AB Which-has bulges in its sides to accommodate theinterior windings associated with the core C. Illustratively, thewindings, as in known constructions, can extend about a middle leg ofthe core and through core windows, as indicated in Figure 5, where thewindings are indicated by the reference character W.

The transformer casing A-B is preferably made of sheet metal, thus tofacilitate stamping operations to produce and shape it, and in theillustrative embodiment it comprises two halfhousings generallyindicated by the respective reference characters A and B. Eachhalf-housing is stamped or shaped to the respective conformationshereinafter described and they can rest, as shown in Figures 1 to 3,against the rcspective side faces of the core C; half-housings A and Band the laminations forming the transformer core C are clamped togetherby any suitable means, such as bolts Ill and nuts I I, which enable thecasing to be taken apart if desired. Rivets or clamps may be usedinstead of bolts and nuts for this purpose.

Half-housing A, as is better seen in Figures 2 and 3, has a bulging ordished-out central portion l2 of substantially rectangularconfiguration, with rounded edges and corners, and as seen in Figures 2and 3, the central portion It extends upwards from a flat marginal orbase portion I3 which rests against one side face of the core C. Asshown in Figures 1 to 3, the bolts pass through this marginal or baseportion of using A. In Figure 2 is indicated a dimension a whichindicates the maximum depth of the bulging or dished-out portion l2,being the distance from the inside face of the base portion l3 to theoutside surface of the dishedout portion [2, which surface (Figures 2and 3) is flat.

Half-housing A has an extension H, to the left in Figures 1 and 2 andtoward the observer in Figure 3, which is formed integrally with and aspart of half-housing A, is slightly tapered as shown, and it ends in asubstantially semi-circular ring-like flange [8; as shown in Figure 2,it overhangs one end face of the core C; its lower overhanging edges(Figures 2 and 3) are substantially in the plane of the inside face ofthe base portion l3, which plane is coincident with the plane of thecore face against which the half-housing A rests. Also, as appears inFigure 3, the extension ll overhangs an end of the core C substantiallyat its midpoint. The center or axis of the semi-circular ring-likeflange [8, while falling substantially in a vertical plane through thecenter of the core C as viewed in Figure 3, is displaced or offsetvertically from the horizontal plane through the center of core C.

The right-hand portion of the tapering extension I! as seen in Figure 2overlies the upper face of the left-hand leg of the core C, providingample passageway for the input leads [6-46, usually heavily insulated asshown, and they can thus overlie that transformer leg, as is shown alsoin Figure 5; these leads, in the illustrative embodiment, are the onesthat are to be connected to the building lighting circuit, usually ofabout volts, and they are connected in any suitable manner to the highvoltage coil of the windings W, illustratively as indicated in Figure 5.

Just behind the half-ring flange I8 as viewed in Figure 3 and to theright as viewed in Figures 1 and 2, the extension H has a semi-circulardepressed portion I! (Figure 2) which is of lesser radius than theportions of the extension l1 to either side of it.

Half-housing B has a dished-out portion l9, in general similar to thedished-out portion I2 of half-housing A, having a base or marginalportion 23 that rests against a side face of the core C where it is heldby thebolts II]. In the dishedout portion is is a generally centrallylocated opening adapted to securely hold a flat piece of insulatingmaterial which serves as a terminal panel 20 provided with binding postsor screws 22, illustratively two in number, to which output leads 2| maybe attached; the binding posts 22 are connected internally of thetransformer structure and in any suitable manner to the low voltage coilof the windings W, that coil supplying lower voltage, illustratively 6volts or 24 volts.

In Figure 2, on the half-housing B, is indicated a dimension b, whichrepresents the depth of the dished-out portion 19, that is, the distancefrom the inside face of base or marginal portion I3 to the outside faceof the flat wall of the dishedout portion l2.

At the left-hand end of half-housing B as viewed in Figures 1 and 2 andat the forward end as viewed in Figure 3, half-housing B has a taperedextension 26 formed integrally with and as part thereof; similarly toextension I! of half housing A, extension 26 terminates in asemicircular ring-like flange 21 and adjacent the latter it has adepressed portion zfi -of lesser radius than those parts of theextension that are to either side of it. The lengths of extensions l1and 26 are the same so that they project beyond an end face (theleft-hand face in Figure 2) of the core C by the same distance.

Unlike extension I! of half-housing A, which is attached to the latterthroughout its semicircumference, extension 26 of half-housing B is cutaway from half-housing B except for a small portion of itssemi-circumference, and because of the above-described offset ofextension I! of half-housing A (see Figures 2 and 3), this relativelysmall uncut portion is left, as indicated'at 39 in Figures 2 and 3,along the line of the-outer edge of the base or marginal portion 23 ofthe half-housing B, so that the semi-circular tapered extension 26 canoccupy a position where it is complementary to the extension l1, namely,in the angle (see Figure 2) between the end face of the core C and theoverhanging extension I! of half-housing A. When the parts are thusassembled, semi-circular or half-ring flanges l8' and 21 form a completecircular opening (see Figure 3); together, the-extensions l1 and '26form a tubular projection from the bulk of the assembled structure, ofsubstantially circular cross-section, and because of the above-describedtaper in each extension, this tubular projection decreases in diameteras its length increases and it terminates in a subdivided annular flangemade up of the semi-circular flanges l8 and 21 with the interveningshort section of reduced radius which is :made .up of the twoabove-described miepii'essed semi-circular portions 11 and 2 6 whichtogether, in effect, form an annular :groove. Moreover, the center lineor axis (of this tubular projection or tube-like extension 1-4-6 isoffset ("see Figure 13) from "the horizontal 1midplane of thetransformer structure (see :also Figure 2)..

,Moreover, the complementary extensions H and '26 dorm a substantiallycircular channel through which the input leads l B-ilt may pass from theinside of the casing "to the exterior thereof. ltn the circular openingformed :by the flanges It and 2? is placed an insulating .disc as withholes to accommodate the input leads :15; as shown in Figure 2, thesemi-circularnanges i 8 and 21 are externally convex, forming a smoothrounded-over exterior and, being externally coonvex, the hang-es 1B and2-1 arethereby internally recessed throughout theirrespectiv-e arcuateextents, each about ltlo'degrees as shown Figure 3, and insulating disc2%, as is better shown in Figures '2 and 3, is seated in thesecomplementary arcuate recesses which thus coact to hold the insulatingdisc 29 transversely of the axis of the tapered tubular ex-tensionformed by the comfilamentary extensions I'l' and 2'6. Also, as shown inFigure 3, the holes -indisc 29 are "spaced apart by a substantialdistance and they thus, also, insulating-1y hold the "input leads-l-E-lil correspondingly spaced apart.

The sma il'uncut portion 39 (Figure "3) through which the extension 26remains joined to the halt-housing B, acts like a hing-e and allows thehalf-ring flange 21'1'20 be displaced substantially radially a directionin line with its "vertical radius as seen in FigureB), relative to C02.p'lementary half-ring flange 18 on the compile mentary extension 11. Thecomplementary extensions i7 "and 26 may thus be spread apart and thetubular extension -I!'2-6, in effect, expanded at its outermost end, andin "the specific illustrative embodiment above described, the connectingportion 38 "between extension 26 and halfhousing 33 being flexible, the"expansion takes place in the direction of the vertical diameter asseenin Figure 3.

Suitable spreader means are provided, preferablyin the formera-screw-or'bol't 3-! that passes through a threaded hole 2t inex'tensionZ5 and which is anchored at a point in extension i"! that is oppositethe threaded hole in the extension 26, whereby "upon turning of thescrew 'or bolt, as by ascrew-driver Where it has a slotted head asshown, the extensions are "spread apart, the tubular extension 15-26being deformed, at its outer end, by enlargement along -the verticaldiameter as viewed in Figure 3. Enterioriy or" the tube-like extensionFF-2t, the boil: or screw 3"] is sheathed "in a sleeve '32 of insulatingmaterial as shown in Figure '2 "(seealso Figures '4, 5, and in order, asappears from Figure 3, "to insulatingly by-pass the insulated inputleads l6-*l5 and between which the bolt '31 extends, the spaced holes inthe insulating disc rs enacting to hold the insulated conductors "it-4tspread apart so that, within the tubular extensions Ill- 26, each can:pass -to one side "of the bzciltfBl.

For purposes of assembly in course "of "marmfa'cture, there are many"advantages 'in offsetting the tubular extension I l'26 so 'thatitshorizontal median plane as viewed in Figures 2 and 3 coincides with theplane of the upper face or the core (I; as seenin Figure 4, assembly andconneotion oi the heavyiihighvol tage leads l s-4 6 are greatlyfacilitated; However, :a disadvantage lies in the that :a direct :pull,to :the flight in Figure 4, :on the external ends of leads iii-16 mightimpose an undesired and detrimental strain on the internal electricalconnections with the usually very thin wires of the high-voltagewinding, with .the risk of :nupturing them. Accordingly I make provisionfor overcoming such risk so that pulling on the leads tit-iii to makethe cormection :to "the parts Within the outlet box D can be safelyeflec'ted, and this I carry out in a manner 'to achieve anchorage eventhough the transformer structure has embodied it atemperature-responsive safety cutout as it at times desirable or"prescribed.

in Figures '4 land 9, I have shown :a preferred form oftemperature-responsive cut-out. comprises :a heavy "fiber plate-likesupport All having a downward extension 42 that extends into theleft-hand core window 43 o'f'the core C. The latter is of the shelltype, having a middle core leg 34 which passes snugly through thewindings W and the heavy fiber winding end plates 45--4B that aresubstantially octagonal, shapedso their right-hand vertical-edge faces,as seen in Figure 4, abut against the inside fac'e'or" the right-handcore leg and their left-hand vertical edge faces are spaced from theinside face of the left core leg by a distance equal to the thickness ofthe fiber support 4'1; the latter rests against the left-hand verticalends of winding plates 15-45 with its downward extension 42 snuglyfitted into the space between the left core leg and these vertical plateends. "Ihefiber support M is thus mounted and held to resist forcestransversely of its plane, particularly forces to the right in Figure 4.Its ends overlie the core C and its upper edge (Figure 9) may beconformed to the shape of the inside face of the bulging part ofhalf-housing A so that when the latter is assembled to the core!) andits counterpart half-housing B, as by the bolts Iii-H3, fiber support 41'is securely clamped between housing part A and thecore C.

Fiber support t! carries 'a'thermally-responsive switch structure whichcomprises two elongated flat metal parts it and it, each on one side ofsupport' ii, to which they areclamped at one end by a hollow rivet oreyelet 5d so as to extend toward the other end where they overlie anaperture 5| (Figures 9 and 10). A combination Washer and bushing ll ofinsulating material insulates part it from the eyelet do and part 48.One of the parts, 4?, has an area or portion 47 illustratively circular,that is stamped or pressed out of its plane so as toprojectinto theaperture 51, acting as a guide to resist any tendency of part ill toswing, about the rivet 59, out of juxtaposition to the other switch part&8. The latter is prevented from swinging about the rivet 5'!) by anextension til that is bent into a cut-out ll in'support ii. The freeends of parts ll' l8 are thus maintained opposite each -other,at theaperture at, where each, as shown in Figure 1 0, has a "contact'point ofsuitable alloy for engagement with each other to close an electricalcircuit. Intermediate its ends, support M has a large aperture '52 whichextends above and below the plane of the upper face of core C as viewedin Figures '3 and i and thereby substantial lengths of the switch partsii-58 are insured of-exposure to the temperature created inside thehousing A--B by the operation of the windings Wand .by heatloss es inthacore. 0.

{one "of the switch parts, such as part :48, is

bimetallic so that, being clamped by eyelet 50 at one end, it bows, uponincrease in temperature, in a direction to move its other end away fromthe plane of support 4| and hence away from and out of contact with theend of companion switch part 41 exposed in aperture 5|, thus breakingthe circuit at the contact points. When connected in circuit with thehigh-voltage coil of windings W, the circuit can thus be broken upontemperature rise due to overloading. Switch part 41 is provided with atab 41 to which the thin lead wire from one end of the high-voltagewinding is secured, as by wrapping and soldering, after passing itthrough a hole in end plate 45 of the windings W. One of the heavylead-in conductors IE, after stripping its end of insulation, isprojected through the eyelet 50, then bent over, and soldered to theeyelet. Pull or stress exerted on that lead-in conductor I6 is resistedby the rigidly clamped fiber support 4| and is not exerted on the thinlead from the coil; were plate 41 to yield, it would yield to the rightin Figure 4 and could not tension the thin lead-in from thecoil.However, provision is also made to relieve the fiber support 4| fromsubstantial stresses in that the lead-in connected thereto may be heldin a manner about to be described.

Resting upon the upper face of middle leg M (Figures 4 and 3) is asuitably heavy sheet-metal plate 54 (Figure 7 provided with end tongues55-55 and overlying it is an I-shaped plate (Figure 8) of insulatingmaterial, of the same width but longer, being cut out at Ii"! and 51both are tightly held and anchored between the leg 45 and windings W,being put in place upon assembly of pre-formed windings W to the middleleg M1 with the fiber sheet 51 toward the inside of windings W. Tongues55--55 are bent upwardly into the cut-outs 51 and 51 of the insulatingplate 51, preventing relative displacement between the two.

Where the transformer includes a cutout 41-48 as above described, and towhich one of the heavy input-leads |t is anchored, that lead is passedover the insulating plate 51 and between the tongue or lug 55 andwinding end plate 45, as shown in Figure l, whence the tongue 55 is bentover it to clamp it tightly against the anchored metal plate insert 54,with the fiber plate 51 interposed. Thus the fiber support is protectedagainst the effect of substantial stress that might be imposed on thlead-in. The other input-lead iii. or, in case the structure does notinclude the cut-out switch 414t, both inputleads |"5-|6 are secured inthe manner now described with respect to the lower lead H; as seen inFigure 4.; the heavy lead is first bent back upon itself to form a hookH, the short end of which is inserted between the then-upstanding tongue56 and winding end plate is, whence the tongue 55 is bent over it andforced home toward the metal insert plate 54 to clamp the short endbetween tongue 56 and the metal plate 54 with the insulating plate 51interposed therebetween. The resultant anchorage is strong and does notslip, for the heavy lead is hooked around the tongue and the tongueclamps and holds the short end of the hook against unbending and withoutunbending no slipping takes place. No stress is transmitted to the thinhigh-voltage coil lead wire which, after passing through a hole in endplate 46, is soldered to the bared wire of short end of the hook H.

When the fiber support 4| is clamped between the core C and half-housingA, strains are frequently set up in the part 4| and it is sometimesdistorted so that an initial setting of its bimetallic part forfunctioning to open the circuit at the desired temperature is disturbed.This is in part counteracted by the provision of the apertures 5|-52which remove a major part of the fiber support 4| from inbetween theswitch arms 41--48, giving their major portions a sort of freefloatingeffect. Upon final test-checking, however, when assembly is completed,any departure in setting is corrected by an arrangement that does notrequire taking the half-housings apart. In switch part 48 is threaded ascrew 58 whose free end abuts the fiber support 4| (Figures 4 and 9),and in half-housing A I provide a small round hole 59 (Figures 2 and l)which is coaxial with the axis of the screw 58. A small screw-driverinserted through the hole 59 serves to turn screw 58, which is close tothe eyelet support 50, to strain the switch part 48 in a directiontoward or away from its companion switch part 41, as the case may be, toeffect circuit-opening at the de sired temperature. The structure isthen ready for installation.

The above-described floating form of support for the coacting ends ofthe parallel switch elements 41-48, furthermore, serves to tend topreserve the temperature setting should the lead-in wire l6 anchored tothe composition fiber or plastic support 4| strain the latter; anystress causing such strain is imposed on support 4| at the eyelet 50 bywhich elements 41-48 are secured, and such strain does not disturbeither element relative to the other and, at the most, shifts the two asa unit, and this action is aided in that the intervening portions ofsupport plate 4| are cut away so as not to impede such shifting.

The inner end of the spreader bolt 3| bears against the rigid extensionH at a point opposite the threaded hole 26 in the movable extension 26and is suitably anchored in the extension |1. In one form the bolt 3|,at the end opposite its head, is anchored in extension [1 part-way alongits length so that turning the bolt 3| spreads extension 26 away fromextension H or draws it toward extension |1, depending on which way thebolt is turned. An illustrative arrangement of this kind is shown inFigure 6, where an intermediate portion of the bolt passes through ahole, which thus forms a seat or socket, in a depression in the wall ofextension l1, its end is externally headed over, and such arrangementanchors the free end of the bolt against sidewise displacement under thestress of spreading one extension away from the other. Or the bolt maybe anchored against such sidewise displacement, by simply having itsinner end portion seated in an internal recess or seat in the wall ofextension H at a point opposite the threaded hole 26 in the extension26, as indicated in Figure 5, where the internal seat or socket isformed in a depressed portion of the sheet metal of the extension l1.

Standard outlet boxes, such as is shown at D (Figures 1 and 2), consistof a back wall 33, four side walls 34, 35, 36, and 31, and a cover plate(not shown). The walls are provided with knock-outs seated in theseveral openings 33 that are usually provided in each wall (only one isshown in the back wall in the interest of simplicity); these are of theusual type and, as is.

known, any one or more knock-outs may be removed to expose and makeavailable the desired hole or holes through which the wiring a scissa oithe1'building: circuit; or circuits is usually brought into: the:outletbox. for electrical interconnection. In standard outlet boxes, thedis.- tances: from. each of the: openings or holes 38 in. the.side-walls 34', (E'r,. 3 t.,v and 31* to: the back of the backwall. 33-is; fixedi and invariable, and when the: box. is. secured with; its backwall 33 against a. wall surface. or wall; 39; as. by screws 40 (Figure.2);, these openings 38 in; the; side walls are all spaced; from. theface. of; the wall Bit by the. same. invariable distancev which, fromthe. center i of. the. hole 38. to. the face of" the wall 38-,indicated. in Figure 2 by the dimension or Safety rules against firehazards require that in. mounting atransformer in relation to,.asurfacemounted. outlet. or panel box for connection of its high voltageterminals to. circuit conductors within the box, the transformer mustnot, be given a position relativev to: the wall 39', which is: notinfrequently a wood panel, less. than a prescribed minimum, for example,one-quarter of an: inch. In Figure-2 a. dimension d indicates: a spacingof the. transformer from the wall 39 bya distance not less than therequired minimum for safety. Illustratively, the distance 0, beingthespacing of the. centers. of the side Wall holes 38 from the face of wall39, may be seven-eighths of an inch. According to. certain features ofthis-invention, it. is possible to make certain that the transformercannot be. assembled to the outlet-or panel box without meeting at leastthe minimum safety requirement of spacing of the transformer fromthewall 39.

As above noted, the depressed halfecircular portions H and ZEi of theextensions. I51: and I 25 together form an external annular groove orneck, and as appears from Figures 1 and 2, the radius of' this annulargroove is commensurate with the radius ofa hole 35 in the outlet box,one of which holes (the center one in the wall 35' of Figure 1) is shownwith its-knock-out removed and hence with its ring-shaped wall exposed,the width of the latter being about the same as the thickness of themetal of the side wall 35.

The longitudinal axis of the tube-like extension Il'--2'5 liessubstantially in the plane of the upper face of the core C, as viewed inFigures 2 and 3-, and against which face the half-housing'A rests;-as'appears clearly in Figures 2- and 3', all parts of the transformerstructure that extend upwardly from or beyond this upper face of core Cand hence extend upwardly from the longitudinal axis of the tubularextension IT-26, fall within the dimension :1 (Figure 2) which, wheredimension 0 is illustratively seveneighths of.v an inch and the minimumvalue of the spacing dimension d is one-quarter of an inch, isfive-eighths of an inch. But, as seen in Figure 3, all parts that extendto theright or to the left of the vertical plane through thislongitudinal axis of the tubular extension 26, extend; beyond that axismaterially more than the sum of the dimensions a and 01. Also, all partsthat extend below, in Figures 2 and 3, the horizontal plane through thislongitudinal axis of. the tubular extension, have an extent greaterthanthe sum of the dimensions a and d. Though, because of symmetry ofinternal construction in the illustrative embodiment, dimensions a and bin- Figure 2,, being the respective depths of the dished-out, portions.12 and IQ of the half-housings. A and B, respectively, are equal, theoffsettingof; the. half-circular extension I! upwardly toward the.horizontal plane of the fiat face:- of the. dishedeout, portion. l2 andthe oft: setting upwardly. and in: the same direction. (Figures 3; and.Z) of, the half-circular extension 2.5 from the fiat face of the,dished-out: portion l9 are such, that, in the illustration, the dimen:sion. a; (Figure- 2) is less than the dimension 0 by at least thedimension, ti, and the dimension 1 (Figure- 2-)-. exceeds dimension 0.

Accordingly, and asrseen; in- Figure 3, the long i tudinalaxis of. thetube-litre extension H72 6, is spaced. from. thetwo-pa-rallel sides ofthe structure (being, inI effect, the left. and right-hand side-faces-ofthe coreC. in. Figure 3) by adistance greater than the dimension. 0,and. is spaced; from the. plane of the bottom face of the dished outportion. t9 of the housing part B alsoby adis-tance greater than thedimension 0, butis spaced. fIom the-opposite-or upper, parallel face ofthe dishedoutportion l2 of thehousing part A by: a distance that. isless than the me si 0.- by an. amou t at least equal to. the; safetydimension d. 'Ijhat means that. the transformer structure can have itstube-like, extension l-'I2B. entered into the open; hole- 38; inthesidewall 35 of the outlet box I) only when the. half-housing part A;with its half-circular extension I"! is brought to, face the wall 39.

The input leads. LET-t6, arefirst entered through the; open hole; 331and thereupon the sub-dimmed tube-like extension, 6 1725. is enteredinto the open hole 3118: through which the half-circular roundedmverflanges t8, and. 21 just about, pass, withthe extension Minot spread,away. from extension 55?, which; is-.-the position of the 13. 1. 28 asshown; in Figure. 3: nd. in which position the flanges l8 and, 21 form.a complete circle, as above noted. As indicated. in Figure 2, thetapered Walls oftha extension; lite-216. are such that they limit, theentry;- of the; tubular extension lp1-.--2-6 into the hole 38,. to apoint where the annular groove f med by e. d p ss d p io e and 2 6? arein; juxtaposition to the ring-likev wall of the hole. 3.8, whereupon thebolt 3| is; turned. to spread extensions, H- and 2,6.so. thatthedehressed or grooved portio s tl andzfi are forced; radially apart andagainst the edge-like wall of thev hole 3.8-. he p ea i act on: us-aciered expand the roundedrover flanges t8, and 2 1., to, the left or onthe inside or the, outlet box wall to (Figure to.v a dimension greaterthan. the fixed, dimension of, the hole: 38:. The transformer structureis; thus; firmly.- secured; to; the wall 35. of the box and is firmlyheldplace. Thereafter the necessary wire connections are. made totheinput leads l(i|tf. It is to-be-noted that the transformer structure maythus. be mounted in position quickly andwith; a mining-um of manualoperations and that what. operations are performed to. secure. it inplace are carried on outside of the box D, excepting: for making. thewire connections. Moreover, at least the minimum required spacingof thestrueture'from the wall 39 is practically automatically achieved.

he appears from Figures-v 1 and 2, the head of thescrew 3 I; is exposedat'that face or side of the transformer structure that is opposite thatface which, for safety reasons, it is desired to have spaced from thoughfacing toward. the wall 39,

and. thus theonly position from which the screw head. is mostconveniently accessible for spreading the sub-divided gripping parts isthe one which gives the desired spacing of the structure from the. Wall.

The amount of spreading, at the outer end portions of the tube-likeextension I'm-26; to

, l1 tightly secure the structure against the walls of the hole 38, neednot be very great, as appears upon comparing Figure 3 (unspread) withFigure 2 (where the parts are spread apart), and the spreading action,which takes place by a slight counter-clockwise pivoting of theextension 26 about the hinge-like bending of the portion 30, isaccompanied by a tilting of the plane of the half-circular flange 21 outof alignment with the plane of the companion half-circular flange [8, asshown in Figure 2; the insulating disc 29 thus remains dependably heldwithin the companion half-circular recesses in the flanges 18 and 21,being in effect gripped by the side walls of these arcuate recessesbecause of the justmentioned relative tilting that takes place, all asshown in Figure 2.

The transformer structure, however, is adaptable for alternative methodsof mounting independently of the outlet box and also within known safetyregulations, and accordingly halfhousing A is provided with a downwardextension (Figure 1) below the core C, being integral with the base ormarginal portion l3 and at its lower end being bent outwardly atapproximately a right angle to form a flange or pedestal 14 providedwith holes or slots IE to accommodate screws, bolts, or other fasteningdevices. Companion to the pedestal I4 is a similar and juxtaposeddownward extension (Figure 1) of halfhousing B, from the base ormarginal portion 23 thereof, being bent outwardly at right angles toform a pedestal 24 with holes or slots 25. Pedestals I4 and 24 are inthe same plane, and

as better appears in Figures 2 and 3, they extend 1.-

from the base parts I3 and 23, respectively, by a distance approximatelythe same as the depth of the dished-out portion l2 and dished-outportion 19, respectively, of the housing parts A and B. By means ofthese pedestals the transformer structure may be secured to any suitablesupport.

These pedestals do not interfere with the desired mounting of thetransformer structure to an outlet box as above described, and they cansimply be disregarded when such mounting is effected. Desirably, and asabove indicated, where the transformer structure has a face toward thewall 39 that is flat and of substantial area, as is the case with theflat portion of the dished-out portion 12 of the housing part A, suchface is parallel to the wall face 39 so that the spacing distance d isuniform throughout, and thus a safety spacing from the wall face 39 atall internal parts of the transformer that generate heat is broughtabout. As is known, it is the windings and the core C which can becomeunduly heated, as from overloading or a defect in a circuit somewhere.

I may, however, make provision to guard against installing thetransformer initially with its back face out of parallelism with thewall 39, or to guard against possible shift of the structure out of suchparallelism. Thus I may provide the transformer structure with suitablerelatively small and spaced elements that are engageable with the faceof the wall 39; these may comprise lateral tongue-like extensions l4 andl4 near the respective ends of the right-angled ange i4, and as shown inFigure 2 they extend beyond the dimension 1: by a distance which neednot be greater than the minimum safety dimension d. Spaced upwardly fromthe plane of these extensions I4 and l4 are two extensions [3 and l3that are integrally formed with a right-angled extension l3 (seeFigure 1) of the upper portion of the base or marginal portion 23 of thehalfhousing B and which overlies the upper face of the core C;extensions I3 and 13 project beyond the rear face of the core C by adistance equal to the sum of dimension 0. and safety dimension d.

The outer edges of all four extensions I4, I4 i3, and l3 fall in a planewhich is parallel to the axis of the extension "-26, being spacedtherefrom by the distance 0; this plane substantially coincides with theface of the wall 39 when the transformer structure is secured to theoutlet box D and the extensions engage the face of wall 39 atsufficiently spaced points to insure that no such tilting of thetransformer structure about the longitudinal axis of the tubularextension I126 can take place as will make the spacing of anyheat-generating part of the structure less than the desired safetydistance. These extension members can be brought safely into contactwith the wall 39, for the purposes just described, because they are notdirectly subjected to any heat that might be generated internally of thetransformer, and being preferably made integral with the sheet metal ofthe transformer casing or housing and extending away from the latter,they are relatively thin and in effect act to radiate or dissipate tothe atmosphere any heat that might reach them by conduction.

These four tongue-like extensions are scored along the lines indicatedat S, whereby they can be broken off if they are not needed inparticular installations.

It will thus be seen that there has been provided in this invention atransformer construction and mounting therefor in which the variousobjects of this invention, together with many thoroughly practicaladvantages, are successfully achieved. Economy and ease of manufactureof the transformer housing and of its assemblage to the core structureare achieved; for example, the casing or housing may be made up in theform of the two half-housings A and B, utilizing two pieces of metalstock, such as steel or any other suitable metal, and each of these issubjected to a simple series of appropriate stamping operations andassemblage thereof to the other parts as above described effected tocomplete the transformer structure. In installing it, the operations aresimple and speedy and can be carried on with complete safety, having theadditional advantage, also, that installation can be effected withouthaving to contend with loose parts.

As many possible embodiments may be made of the above invention and asmany changes might be made in the embodiment above set forth, it is tobe understood that all matter hereinbefore set forth or shown in theaccompanying drawing is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. In construction of the character described, in combination, an outletbox having a back wall to rest against a supporting surface and sidewalls and having a round aperture in a side wall thereof spaced from thecenter of the aperture to the plane of the back wall of the outlet boxby a distance r, a transformer structure having a core and coactingwindings and an enclosing casing therefor presenting four side faces,said casing having a tubular extension the axis of which is parallel tosaid four side faces of the transformer structure and is displaced fromthree of said side faces by a distance greater than a: and from thefourth side face by a distance less than a: by an amount providing afactor of safety against fire hazard whereby the axis of said tubularextension half housings and has conductors extending therethrough tosaid winding means, and an apertured insulating disc substantiallyclosing off said tubular extension and having said conductors passingtherethrough, each of said half-circular extensions having axiallyspaced means of substantially 180 degrees extent for respectivelyreceiving therebetween opposed peripheral portions of said insulatingdisc, each of substantially 180 degrees extent.

14. A transformer construction for mounting in the round aperture of asupport such as an outlet box or the like comprising a core and coactingwinding means and a casing therefor, said casing having a tubularextension communicating with the interior of said casing and havingconductors extending therethrough from said winding means, said tubularextension being subdivided into opposed arcuate end portions whereby thelatter are receivable in the round aperture of a support and beingsubstantially closed by an apertured insulating disc through which saidconductors pass, said end portions having flange-like means directedinwardly for holding said insulating disc, and means for spreading apartopposed arcuate portions that are at opposite ends of a diameter withoutmaterial spreading. apart of arcuate portions thereof at opposite endsof a diameter that makes a right angle with said firstmentioned diameterand thereby maintain the holding action on said disc by said flange-likemeans.

15. In construction of the character described, in combination, atransformer core of the shell type having windings thereabout, a casingcomprising two half-housings for enclosing said core and windings fromopposite sides of said core, a thermally-responsive switch comprising aninsulating support and two substantially parallel opposed conductiveswitch elements with means insulatingly securing one end of each at onepoint in and to said insulating support whereby the other ends thereofare free for relative circuit-controlling movement, said support havingmeans securing it in fixed relation to said core and said half-housingshaving juxtaposed complementary half-circular extensions which togetherform a tubular extension for the passage of a conductor therethrough,and a conductor extending through said tubular extension and anchored tosaid insulating support at a point substantially coincident with thepoint at which said switch elements are secured thereto.

16. A transformer construction as claimed in claim 15, in which saidinsulating support comprises a plate-like member having a portionextending between said windings and a part of said core with its planeat right angles to the axis of said tubular extension, said switchelements being on opposite sides of said plate-like member and thesecuring means for said switch elements comprising a hollow clampingmeans having said conductor extending thereinto and secured thereto,said plate-like member having portions thereof in between said switchelements cut away whereby the free ends of said switch elements can moveas a unit under straining of said plate-like member at said securingmeans.

17. In construction of the character described, in combination, atransformer core of the shell type having windings thereabout, a casingcomprising two half-housings for enclosing said core and windings fromopposite sides of said core, said half-housings having complementaryhalf- .circular extensions forming a tubular mounting extension, and arelatively heavy conductor passing through said tubular extension andhaving its inner end bent into a hook, said core and windings havingsecured thereto a clamping lug that is bent over the short end of thehook with the axis of bending substantially parallel to the axis of saidtubular mounting extension and to the line of said conductor.

18. In construction of the character described, in combination, atransformer core of the shell type having windings thereabout, a casingcomprising two half-housings for enclosing said core and windings fromopposite sides of said core, said half-housings having complementaryhalf-circular extensions forming a tubular mounting extension, the axisof said tubular extension extending at right angles to the axis of saidwindings and the core portion therein, and two relatively heavy lead-inconductors extending axially through said tubular extension andtransversely of the axis of said windings and terminating in hooks atthe respective ends of said windings, said windings and said coreportion having interposed therebetween a sheet-metal strap terminatingat the respective ends of said windings in bendable lugs respectivelybent over the short ends of said hooks with the axis of bendingsubstantially parallel to the axis of said tubular mounting extensionand to the line of the conductors therethrough.

19. A transformer construction comprising a transformer core havingwindings thereabout and enclosing casing means therefor, with means forclamping the latter and said core together, a thermally-responsiveswitch comprising an insulating plate-like support having an edgeportion seated against said core and an opposed edge portion engaged bysaid casing means whereby said insulating support is clamped between thetwo, asid insulating plate-like support having two relatively longsubstantially parallel opposed conductive switch elements in circuitwith said windings and having means insulatingly secured one end of eachto said insulating support at substantially the same point in theplate-like support and having the free ends thereof juxtaposed to eachother for relative circuit controlling movement therebetween, whereby,should said plate-like support be strained and the portion thereof atwhich said switch element ends are secured be distorted out of normalrelation to the rest of the support, said other ends of said long switchelements are shifted together substantially as a unit.

20. A transformer construction as claimed in claim 19 in which saidparallel switch elements are on opposite sides of said plate-likesupport, the latter having portions thereof in between said switchelements cut away to provide clearance space for relative circuitcontrolling movement between said free ends of said switch elements andfor movement thereof as a unit.

21. A transformer construction comprising a core and windings and havingmounting means projecting therefrom comprising two substantiallyhalf-circular sheet material parts which together form a hollow annulusand means supporting said two half-circular parts in complementaryjuxtaposed relation to form a hollow annulus comprising means rigidlymounting one of them from said core and means supporting the other fromsaid core and having hinge-like connecnection to said other part therebyto permit movement thereof toward or away from the other halfcircuiarpart to change the spacing therebetween and to enlarge or shorten adiametrical dimension of said annulus, a conductor extending from saidwindings through said hollow annulus, and means coacting between saidtwo parts for con trolling the spacing therebetween, whereby saidannulus with said conductor may be entered into a round aperture in asupport and clamped against the peripheral walls thereof.

22. A transformer as claimed in claim 21 in which said last-mentionedmeans comprises a screw having threaded connection with one of saidhalf-circular part and engaging the other.

23. A transformer as claimed in claim 22 in which said screw extendssubstantially diametrically of said annulus and is by-passed by saidconductor, said screw having thereabout an insulating sleeve.

24. A transformer constructed comprising sheet-metal casing means havingtherein a transformer core and windings with a conductor extending fromthe latter, said casing means having means for mechanically connectingit to a support, said means comprising an external sheetmetal annulusprojecting from said casing means,

said annulus having a peripheral flange at its outer end and both saidflange and said end being subdivided into opposed relatively movablearouate portions by slit means extending lengthwise of the axis of theannulus and toward the inner end thereof whereby the resultant arcuateportions thereof are relatively displaceable in a direction toward oraway from the axis of said annulus to dimensionally lessen the outer endand said flange of said annulus for passage of the flange through around aperture of a support and to dimensionally enlarge said flangeafter passage through a round aperture of the support, said conductorextending through said annulus and outwardly through the outer endthereof.

25. In construction of the character described,

in combination, an outlet box having a back wall to rest against asupporting surface and side walls and having a round aperture in a sidewall thereof spaced from the center of the aperture to the plane of theback Wall of the outlet box by a dis tance x, a transformer structurehaving a core and coacting windings and an enclosing casing thereforpresenting four side faces, said casing having mounting means receivablein said round aperture, said mounting means having an axis which isparallel to said four side faces of the transformer structure and isdisplaced from three of said side faces by a distance greater than x andfrom the fourth side face by a distance less than as by an amountproviding a factor of safety against fire hazard whereby said axis andthe axis of said round hole in the outlet box can be brought intocoincidence only when said fourth side face is toward the plane of saidsupporting surface, said mounting means having end portions thatterminate at points on a circle that is of a diameter commensurate withthe diameter of said round aperture and are thereby received in thelatter when said fourth side face of the transformer structure facestoward the plane of said supporting surface, and means for securing saidmounting means to said outlet box side wall with the said end portionsthereof received in said round aperture and with said two axes substantially coincident.

26. In construction of the character described, in combination, anoutlet box having a round aperture in a wall thereof, a transformerstructure comprising a core and windings and a casing therefor, saidcasing having a tubular extension communicating with the interior ofsaid casing and having conductors extending therethrough to saidwindings, said tubular extension having a sub-divided end portionpresenting two relatively movable clamping parts spaced substantially ona diameter commensurate with the diameter of said round aperture andreceivable in said round aperture in the wall of said outlet box forsubstantially juxtaposing said two clamping parts within said roundaperture to substantially diametrically opposite peripheral points ofthe latter, and means for moving one of said two clamping parts relativeto the other in a substantially diametrical direction away from theother and thereby expanding the diametric spacing of said two clampingparts of said sub-divided portion of said tubular extension to clampthem against the inside periphery of said aperture.

27. In construction of the character described, in combination, anoutlet box having a round aperture in a wall thereof, a transformerstructure comprising a core and windings and a casing therefor, saidcasing having a tubular extension communicating with the interior ofsaid casin and having conductors extending therethrough to saidwindings, said tubular extension having a sub-divided end portioncomprising two relatively movable clamping parts spaced substantially ona diameter commensurate with the diameter of said round aperture, saidextension having secured thereto adjacent said clamping parts atransverse apertured insulating plate through which said conductorsextend for passage through said aperture and into said box, said twoclamping parts being receivable in said round aperture in the wall ofsaid outlet box substantially in juxtaposition to substantiallydiametrically opposite peripheral points of the aperture and with saidtransverse insulating plate positioned substantially at said aperturefor insulating passage of said conductors into the outlet box, and meansfor moving one of said two clamping parts relative to the other in asubstantially diametrical direction away from the other and therebyexpanding the diametric spacing of said two clamping parts of saidsubdivided portion of said tubular extension to clamp them against theinside periphery of said aperture and for thereby fixing the position ofsaid insulating plate relative to said aperture.

LEO L. VERKUIL.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,964,945 Helgason et a1. July 3, 1934 2,156,461 RittenhouseMay 2, 1939 2,246,890 Miller June 24, 1941 2,433,511 Goddard Dec. 30,1947

